<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT	MIT License
 * @link    https://codeigniter.com
 * @since    Version 2.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * CodeIgniter Caching Class
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Core
 * @author        EllisLab Dev Team
 * @link
 */
class CI_Cache extends CI_Driver_Library
{

    /**
     * Valid cache drivers
     *
     * @var array
     */
    protected $valid_drivers = array(
        'apc',
        'dummy',
        'file',
        'memcached',
        'redis',
        'wincache'
    );

    /**
     * Path of cache files (if file-based cache)
     *
     * @var string
     */
    protected $_cache_path = NULL;

    /**
     * Reference to the driver
     *
     * @var mixed
     */
    protected $_adapter = 'dummy';

    /**
     * Fallback driver
     *
     * @var string
     */
    protected $_backup_driver = 'dummy';

    /**
     * Cache key prefix
     *
     * @var    string
     */
    public $key_prefix = '';

    /**
     * Constructor
     *
     * Initialize class properties based on the configuration array.
     *
     * @param    array $config = array()
     * @return    void
     */
    public function __construct($config = array())
    {
        isset($config['adapter']) && $this->_adapter = $config['adapter'];
        isset($config['backup']) && $this->_backup_driver = $config['backup'];
        isset($config['key_prefix']) && $this->key_prefix = $config['key_prefix'];

        // If the specified adapter isn't available, check the backup.
        if (!$this->is_supported($this->_adapter)) {
            if (!$this->is_supported($this->_backup_driver)) {
                // Backup isn't supported either. Default to 'Dummy' driver.
                log_message('error', 'Cache adapter "' . $this->_adapter . '" and backup "' . $this->_backup_driver . '" are both unavailable. Cache is now using "Dummy" adapter.');
                $this->_adapter = 'dummy';
            } else {
                // Backup is supported. Set it to primary.
                log_message('debug', 'Cache adapter "' . $this->_adapter . '" is unavailable. Falling back to "' . $this->_backup_driver . '" backup adapter.');
                $this->_adapter = $this->_backup_driver;
            }
        }
    }

    // ------------------------------------------------------------------------

    /**
     * Get
     *
     * Look for a value in the cache. If it exists, return the data
     * if not, return FALSE
     *
     * @param    string $id
     * @return    mixed    value matching $id or FALSE on failure
     */
    public function get($id)
    {
        return $this->{$this->_adapter}->get($this->key_prefix . $id);
    }

    // ------------------------------------------------------------------------

    /**
     * Cache Save
     *
     * @param    string $id Cache ID
     * @param    mixed $data Data to store
     * @param    int $ttl Cache TTL (in seconds)
     * @param    bool $raw Whether to store the raw value
     * @return    bool    TRUE on success, FALSE on failure
     */
    public function save($id, $data, $ttl = 60, $raw = FALSE)
    {
        return $this->{$this->_adapter}->save($this->key_prefix . $id, $data, $ttl, $raw);
    }

    // ------------------------------------------------------------------------

    /**
     * Delete from Cache
     *
     * @param    string $id Cache ID
     * @return    bool    TRUE on success, FALSE on failure
     */
    public function delete($id)
    {
        return $this->{$this->_adapter}->delete($this->key_prefix . $id);
    }

    // ------------------------------------------------------------------------

    /**
     * Increment a raw value
     *
     * @param    string $id Cache ID
     * @param    int $offset Step/value to add
     * @return    mixed    New value on success or FALSE on failure
     */
    public function increment($id, $offset = 1)
    {
        return $this->{$this->_adapter}->increment($this->key_prefix . $id, $offset);
    }

    // ------------------------------------------------------------------------

    /**
     * Decrement a raw value
     *
     * @param    string $id Cache ID
     * @param    int $offset Step/value to reduce by
     * @return    mixed    New value on success or FALSE on failure
     */
    public function decrement($id, $offset = 1)
    {
        return $this->{$this->_adapter}->decrement($this->key_prefix . $id, $offset);
    }

    // ------------------------------------------------------------------------

    /**
     * Clean the cache
     *
     * @return    bool    TRUE on success, FALSE on failure
     */
    public function clean()
    {
        return $this->{$this->_adapter}->clean();
    }

    // ------------------------------------------------------------------------

    /**
     * Cache Info
     *
     * @param    string $type = 'user'    user/filehits
     * @return    mixed    array containing cache info on success OR FALSE on failure
     */
    public function cache_info($type = 'user')
    {
        return $this->{$this->_adapter}->cache_info($type);
    }

    // ------------------------------------------------------------------------

    /**
     * Get Cache Metadata
     *
     * @param    string $id key to get cache metadata on
     * @return    mixed    cache item metadata
     */
    public function get_metadata($id)
    {
        return $this->{$this->_adapter}->get_metadata($this->key_prefix . $id);
    }

    // ------------------------------------------------------------------------

    /**
     * Is the requested driver supported in this environment?
     *
     * @param    string $driver The driver to test
     * @return    array
     */
    public function is_supported($driver)
    {
        static $support;

        if (!isset($support, $support[$driver])) {
            $support[$driver] = $this->{$driver}->is_supported();
        }

        return $support[$driver];
    }
}
